The majority of cigarettes manufactured today have a filter composed of cellulose acetate fibers. Cigarettes having a cellulose acetate filter are typically prepared by using a continuous length of cellulose acetate fiber to prepare a long filter rod, then cutting the long filter rod into a multiplicity of shore lengths, or plugs, to form individual cigarette filters and then preparing a cigarette by attaching these filters to a tobacco column.
The above described process for preparation of cigarettes results in two waste streams of cellulose acetate fiber. The first waste stream results from preparing the cellulose acetate fiber into filter rods and individual filters and is often referred to in the tobacco industry as "plug room waste". Plug room waste typically comes from off specification filters and filters used for quality control.
The second waste material results from improperly manufactured cigarettes and is often referred to in the tobacco industry as "rip room waste". In addition to the cellulose acetate fiber, this material typically contains tobacco, paper and other materials.
These waste materials are currently being landfilled. However, because of the increasing cost of disposal and decreasing landfill space cigarette manufacturers and filter tow suppliers are looking for alternatives to disposal. Thus, there is a growing need for new uses for and suitable processing techniques of filter tow waste. Japanese Kokoku No. Sho. 49 (1974)-6761 discloses adding waste cellulose acetate filter tow to a paper-making process. In that process water is added to a beater machine and waste cigarette filter tow material is added. The resultant slurry is heated to 75.degree. C. and caustic soda is added. The mixture is beaten for an extended period of time during which the pH of the solution drops from 11-12 to 6-7. This results in a reduction of the degree of acetylation of the cellulose acetate to 10-30% acetic acid. This is removal of over 50% of the acetyl from cellulose acetate. This treatment allows a paper-like sheet with high cellulose acetate content to be produced.
Other processes are known for uses of the waste filter tow material. U.S. Pat. No. 5,328,934 describes a process to upgrade the ripper room waste by a separation and supercritical fluid extraction. The product from this process is intended for dissolution in a cellulose acetate solvent.
Only the Japanese patent application mentions the use of the filter rods in paper. However, this reference requires a very deep hydrolysis. This level of hydrolysis is undesirable for several reasons. The loss in weight of the acetic acid removed lowers the yield of the process. The resultant acetic acid must be treated or recovered from a dilute aqueous stream. The deep hydrolysis also removes many of the potential benefits such as improved bulking or moldability which are derived from putting cellulose acetate, a thermoplastic, into paper.
Y. Fahmy and S. El-Kalyoubi ("on Fibrous Acetylation of Cellulose. Acetylation of Paper Pulps", Cellulose Chemistry and Technology, 4, 1970, pages 613-619) discloses producing a paper additive by acetylation of cotton and rice straw pulps followed by hydrolysis. Accordingly to Fahmy the acetylation is necessary to insure homogeneity of acetyl group distribution throughout the fiber, even after hydrolysis. Only fibers with homogeneous or near homogeneous acetyl group distribution have the properties disclosed by Fahmy.
Several articles describe repulping of wet-strength paper (Pahl, Brian L. and Herbert H. Espy, "Advanced Topics in Papermaking With Alkaline-Curing Polyamide Wet-Strength Resins", TAPPI Seminar Notes--1987 Advanced Topics in Wet End Chemistry, 1987, pages 77 to 82, Espy, Herbert H., "The Chemistry of Wet-Strength Broke Repulping", Progress in Paper Recycling, 1, Aug. 1992, pages 17 to 23). These articles state that repulping requires either 1) hypochlorite treatment at 120.degree.-130.degree. F. and a pH of 6.5 to 7.0 or 2) caustic treatment at a temperature of 160.degree. F. and a pH of 11 to 12.
U.S. Ser. No. 08/375,140, filed herewith, (Docket 70145) discloses a process for preparing a similar product using either cellulose acetate filter tow as the feedstock.